Yeah, I have one myself. He was a hitchhiker on a piece of live rock I bought. I only realized he was in the tank some time after, when I was night feeding. I have just moved my tank in the past couple of weeks to another room in my house. When I took out the rock he was there. I put him back in after the move, I am now thinking I shouldn't have. You never see them, usually not even at night and if you do, it's only for a second. Now that I am thinking about it, If I didnt have so much rock in the tank, I would probably pull him.